Permeate flow paterns

ABSTRACT

Embodiments of the present invention provide the integration of arbitrary flow directing patterns, deposited or integrated on or into the porous permeate spacer in a spiral-wound membrane separation element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 U.S.C. 371 ofPCT application PCT/US2017/052116 filed 18 Sep. 2017, which claimspriority to U.S. provisional application 62/397,142, filed 20 Sep. 2016.Each of the foregoing is incorporated by reference herein.

The present invention is related to that described in U.S. provisional61/771,041, filed Feb. 28, 2013, and PCT/IB2014/060705, which areincorporated herein by reference.

BACKGROUND Field of the Invention

The subject invention relates to a permeable membrane system utilizedfor the separation of fluid components, specifically spiral-woundmembrane permeable membrane elements.

Description of Related Art

Spiral-wound membrane filtration elements well known in the art consistof a laminated structure comprised of a membrane sheet sealed to oraround a porous permeate spacer which creates a path for removal of thefluid passing through the membrane to a central tube, while thislaminated structure is wrapped spirally around the central tube andspaced from itself with a porous feed spacer to allow axial flow of thefluid through the element. While this feed spacer is necessary tomaintain open and uniform axial flow between the laminated structure, itis also a source of flow restriction and pressure drop within the axialflow channel and also presents areas of restriction of flow and contactto the membrane that contribute significantly to membrane fouling viabiological growth, scale formation, and particle capture. In pressureretarded osmosis (PRO), forward osmosis (FO), and reverse osmosis (RO)applications, flow paths in the feed spaces and the permeate spacer canbe beneficial to optimal system operation.

Improvements to the design of spiral wound elements have been disclosedby Barger et al. and Bradford et al., which replace the feed spacer withislands or protrusions either deposited or embossed directly onto theoutside or active surface of the membrane. This configuration isadvantageous in that it maintains spacing for axial flow through theelement while minimizing obstruction within the flow channel. It alsoeliminates the porous feed spacer as a separate component, thussimplifying element manufacture. Patent publication numberUS2016-0008763-A1, incorporated herein by reference, entitled ImprovedSpiral Wound Element Construction teaches the application of printedpatterns on the back side of the active surface of the membrane sheet,or directly on the surface of the permeate spacer.

The following references, each of which is incorporated herein byreference, can facilitate understanding of the invention: U.S. Pat. Nos.3,962,096; 4,476,022; 4,756,835; 4,834,881; 4,855,058; 4,902,417;4,861,487; 6,632,357; and US application 2016-0008763-A1.

DESCRIPTION OF THE INVENTION

In some spiral-wound membrane separation applications which involveserial flow through the permeate spacer layer of successive elementssuch as in the PRO patent listed above, it is advantageous to have lowerresistance to flow than what is exhibited by traditional woven permeatespacer fabrics, while maintaining other characteristics includingresistance to deformation under high external pressure. Additionally,the ability to tailor flow channels of arbitrary shape within thepermeate spacer can allow for controllable distribution of flow throughthe permeate spacer layer. Embodiments of the present invention providefeatures printed, deposited onto or integrated into the porous permeatespacer to create positive feed channels in the permeate spacer. Inadditional example embodiments, the material creating the channels cancomprise photopolymers, hot melt polyolefins, curable polymers oradhesives, or other materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view and a side view of a variety of features printedinto the interstitial space of a permeate spacer mesh and of featuresprinted both into and on top of the mesh.

FIG. 2 is a cross section view of a 3D printed material in theinterstitial space of a permeate spacer with conventional feed spacerbetween the adjacent layers.

FIG. 3 is a cross section view of a 3D printed material in theinterstitial space and protruding above the permeate spacer whichembosses the membrane sheet to form a flow channel in place of theconventional feed spacer.

FIG. 4 is a cross section view of a 3D printed material in theinterstitial space and protruding through the permeate spacer betweentwo sandwiched sheets of feed spacer producing a more free flow pathbetween the adjacent permeate spacer sheets with conventional feedspacer between the adjacent layers.

FIG. 5 is a cross section view of a 3D printed material in theinterstitial space and protruding above the permeate spacer between twosandwiched sheets of feed spacer producing a more free flow path betweenthe adjacent permeate spacer sheets. The protrusions adjacent to themembrane sheet emboss the membrane to form a flow channel in place ofthe conventional feed spacer.

FIG. 6 is a view of flow control features deposited in to theinterstitial spaces of a permeate spacer within a spiral-wound PROmembrane element.

MODES FOR CARRYING OUT THE INVENTION AND INDUSTRIAL APPLICABILITY

Referring initially to FIG. 1, a single deposited feature or pluralityof deposited features 10 such as posts, islands, straight, curved, orangled line segments or continuous lines, or other complex shapes can bedeposited into 16 or through and onto the surface of the permeate spacermesh 12 or printed or otherwise applied into the interstitial spaces ofthe permeate spacer to create arbitrary flow paths 14 in the permeatespacer, or can be introduced into the permeate spacer during themanufacturing process of the porous permeate spacer layer. The flowchannels created in the permeate spacer can also incorporate featuresprotruding above the surface of the permeate spacer to createprotrusions on top of the permeate spacer 18. As shown in FIG. 3, suchprotrusions can be used to act to emboss 30 the surface of the membranesheet adjacent to the permeate spacer 20 to create a separation betweenthe membrane and spacer with the flat bottom membrane 22 of the adjacentlayer. They can be used to direct flow 26 through the permeate carriermesh and can also be used as a spacer between adjacent stacked sheets ofpermeate spacer to provide lower resistance to fluid flow 40 throughthis permeate spacer stacked layer, as shown in FIG. 4. Additionally athicker two-layer permeate spacer can be produced by stacking one layerwith features printed in or through and above the spacer on top of alayer of permeate spacer that has features printed through and above itto create interstitial spaces 42 to allow significantly freer flowthrough these spaces between the permeate spacer than flow through thepermeate spacer mesh itself, as shown in FIG. 4 and FIG. 5.

Referring to FIG. 6, in some designs of a spiral wound PRO element, acenter tube 60 containing a flow separator 62 facilitates liquid flowfrom the inlet flow 68 through inlet holes 70 into the permeate spacermesh. The printed features are used to direct and regulate flow throughthe permeate spacer to optimize flow and mass transfer between theliquid within the permeate spacer and the cross flow feed before thereturning permeate flow returns through the outlet holes in the centertube 64 and joins the outlet flow from the center tube 66. In caseswhere two layers of spacer mesh are used separated by raised features onone layer, the spaces between the layers will create pathways of lowresistance to flow, and thus lower pressure drop along the pathways,while still allowing adequate flow through the permeate spacer to themembrane surface to provide adequate mass transfer.

In an example embodiment the deposited features are used to formarbitrary flow paths through the permeate spacer and a conventional feedspacer mesh is used to separate the adjacent layers within the spiralwound element.

In an example embodiment the deposited features are used to formarbitrary flow paths through the permeate spacer and the embossedfeatures create spaces in the brine feed channel that otherwise replacefeed spacer mesh material that is currently used in the art offabricating spiral wound membrane elements.

In an example embodiment two layers of permeate spacer are stacked ontop of one another instead of using a single layer with the depositedfeatures forming arbitrary flow paths through the permeate spacer andthe protrusions deposited on one or both layers create a space betweenthe layers that creates significantly lower resistance to fluid flowthan the permeate spacer material itself while a conventional feedspacer mesh is used to separate the adjacent layers within the spiralwound element.

In an example embodiment two layers of permeate spacer are stacked ontop of one another instead of using a single layer with the depositedfeatures forming arbitrary flow paths through the permeate spacer andthe protrusions deposited on one or both layers create a space betweenthe layers that creates significantly lower resistance to fluid flowthan the permeate spacer material itself while the embossed featurescreate spaces in the brine feed channel that otherwise replace feedspacer mesh material that is currently used in the art of fabricatingspiral wound membrane elements.

The height and shape of the features can be configured to provide flowpaths within the permeate spacer and spacing for embossed or protrudingfeatures appropriate to free flow in their respective flow regimes. Thefeatures do not need to be entirely solid and can contain some degree ofpermeability, depending on the printing materials and techniques used.Some amount of permeability can be acceptable because the patterns aremade to direct flow but do not need to entirely separate flow. A smallamount of flow or diffusion across the patterns that do notsubstantially affect bulk flow can be acceptable in some applications.

Those skilled in the art appreciate that the features can be comprisedof various materials that are compatible with the separated fluid andthe permeate spacer including, but not limited to, thermoplastics,reactive polymers, waxes, or resins. Additionally, materials that arecompatible with the separated fluid but not compatible with directdeposition to the permeate spacer, including, but not limited tohigh-temperature thermoplastics, metals, or ceramics, can be pre-formed,cast, or cut to the proper dimensions and adhered to the surface of thepermeate spacer with an adhesive that is compatible with the permeatespacer.

Those skilled in the art appreciate that the features can be depositedby a variety of techniques. Traditional printing techniques such asoffset printing, gravure printing, and screen printing, can be suitable,although there can be thickness and geometry limitations with thesedeposition techniques. Thicker features can be deposited bymicrodispensing, inkjet printing, fused deposition, or via applicationusing an adhesive that can include roll transfer of sheet orpick-and-place of individual features.

The present invention has been described in connection with variousexample embodiments. It will be understood that the above description ismerely illustrative of the applications of the principles of the presentinvention, the scope of which is to be determined by the claims viewedin light of the specification. Other variants and modifications of theinvention will be apparent to those skilled in the art.

We claim:
 1. An assembly comprising: (a) a first permeate spacer layer,comprising a first material having a first permeability, and having afirst plurality of features comprising a second material having a secondpermeability, disposed within the first permeate spacer layer extendingfrom a first surface of the first permeate spacer layer, through thethickness of the first permeate spacer layer, and above a second surfaceof the first permeate spacer layer by a distance, where the firstsurface is opposite the second surface, wherein the first plurality offeatures provide flow paths within the first permeate spacer layer, andwherein the second permeability is less than the first permeability; (b)a membrane, disposed adjacent to the second surface of the firstpermeate spacer layer such that the first plurality of features embossthe membrane; (c) a second permeate spacer layer, comprising the firstmaterial, and having a second plurality of features comprising thesecond material, disposed within the second permeate spacer layerextending from a first surface of the second permeate spacer layer andthrough the thickness of the second permeate spacer layer; wherein thefirst plurality of features extend beyond the first surface of the firstpermeate spacer layer, the second plurality of features extend beyondthe first surface of the second permeate spacer layer, or both; andwherein the second permeate spacer layer is disposed adjacent the firstpermeate spacer layer such that the first plurality of spacers, thesecond plurality of spacers, or both space the first surface of thesecond permeate spacer layer apart from the first surface of the firstpermeate spacer layer.
 2. A reverse osmosis filter element comprising anassembly as in claim 1 spirally wound about a central fluid flowchannel.
 3. A method of making a reverse osmosis filter comprisingmaking an assembly as in claim 1, and spirally winding the assemblyabout a central fluid flow channel.
 4. A method of producing anassembly, comprising: (a) providing a first permeate spacer layercomprising a first material having a first permeability; (b) depositinga plurality of features comprising a second material, having a secondpermeability, into the first permeate spacer layer, wherein the featuresextend from a first surface of the first permeate spacer layer, throughthe thickness of the first permeate spacer layer, and above a secondsurface of the first permeate spacer layer by a distance, where thefirst surface is opposite the second surface, wherein the firstplurality of features provide flow paths within the first permeatespacer layer, and wherein the permeability of the second material isless than the permeability of the first material; (c) providing amembrane; (d) placing the membrane adjacent the second surface of thefirst permeate spacer layer such that the first plurality of featuresemboss the membrane; (e) providing a second permeate spacer layer,comprising the first material; (f) depositing a second plurality offeatures comprising the second material into the second permeate spacerlayer, wherein the features extend from a first surface of the secondpermeate spacer layer and through the thickness of the second permeatespacer layer; (g) wherein the first plurality of features extend beyondthe first surface of the first permeate spacer layer, the secondplurality of features extend beyond the first surface of the secondpermeate spacer layer, or both; (h) placing the second permeate spacerlayer adjacent the first permeate spacer layer such that the firstplurality of spacers, the second plurality of spacers, or both space thefirst surface of the second permeate spacer layer apart from the firstsurface of the first permeate spacer layer.